Base station, user equipment and wireless communication method

ABSTRACT

Provided are a base station, user equipment and wireless communication methods related to DCI design for blind detection. A base station comprises: circuitry operative to align, for each DCI of a first group of DCIs, one of the size of the DCI of the first group and the size of a selected DCI of a second group of DCIs with the other, if the size of the DCI of the first group is different from the size of each DCI of the second group of DCIs, wherein the selected DCI of the second group is a DCI whose size is closest to the size of the DCI of the first group among DCIs of the second group having sizes larger than the size of the DCI of the first group or a DCI whose size is closest to the size of the DCI of the first group among DCIs of the second group having sizes smaller than the size of the DCI of the first group; and a transmitter operative to transmit the first group of DCIs and the second group of DCIs after the size alignment by the circuitry to a user equipment, wherein the size alignment is based on a rule which is known by the base station and the user equipment beforehand.

BACKGROUND 1. Technical Field

The present disclosure relates to the field of wireless communication,and in particular, to a base station (eNodeB), a user equipment (UE) andwireless communication methods related to DCI (Downlink ControlInformation) design for blind detection.

2. Description of the Related Art

Dynamic scheduling of sidelink (SL) transmission according to an eNodeBbased scheduling resource allocation mode has been specified for V2V(Vehicle to Vehicle) communication so far and a sidelink DCI format hasbeen designed for the dynamic scheduling of sidelink. FIG. 1schematically shows an exemplary scenario in which sidelink resourcesare dynamically scheduled by an eNodeB for V2V communication. As shownin FIG. 1, communication may be performed between two vehicles 102 and103 via sidelinks as shown by two thick arrows noted as “SL”. Theresources for sidelink transmission between the vehicles 102 and 103 maybe dynamically scheduled by eNodeB 101 through the sidelink DCI formatas described above. Specifically, communication may also be performedbetween each of two vehicles 102 and 103 and eNodeB 101 as shown byrespective thin arrows noted as “DL” or “UL”. For example, the vehicle102 may receive the sidelink DCI from eNodeB 101 via downlink so as toperform the communication with the vehicle 103 via sidelinks based onthe received sidelink DCI.

Based on latest 3GPP (The 3rd Generation Partnership Project) progress,semi-persistent scheduling (SPS) would be supported for V2V sidelinktransmission in order to satisfy periodic traffic like CAM (CooperativeAwareness Message). Thus, sidelink SPS and the dedicated DCI formatthereof are under discussion in 3GPP.

SUMMARY

One non-limiting and exemplary embodiment provides DCI design to reduceblind detection times.

In a first general aspect of the present disclosure, there is provided abase station, comprising: circuitry operative to align, for each DCI(Downlink Control Information) of a first group of DCIs, one of the sizeof the DCI of the first group and the size of a selected DCI of a secondgroup of DCIs with the other, if the size of the DCI of the first groupis different from the size of each DCI of the second group of DCIs,wherein the selected DCI of the second group is a DCI whose size isclosest to the size of the DCI of the first group among DCIs of thesecond group having sizes larger than the size of the DCI of the firstgroup or a DCI whose size is closest to the size of the DCI of the firstgroup among DCIs of the second group having sizes smaller than the sizeof the DCI of the first group; and a transmitter operative to transmitthe first group of DCIs and the second group of DCIs after the sizealignment by the circuitry to a user equipment, wherein the sizealignment is based on a rule which is known by the base station and theuser equipment beforehand.

In a second general aspect of the present disclosure, there is provideda user equipment, comprising: a receiver operative to receive a firstgroup of DCIs and a second group of DCIs from a base station; and acircuitry operative to blindly detect the first group of DCIs and thesecond group of DCIs so as to perform transmission and/or receptionbased on a rule which is known by the base station and the userequipment beforehand, wherein said rule indicates that before beingreceived by the user equipment, the first group of DCIs and the secondgroup of DCIs has been subject to size alignment comprising: aligning,for each DCI of the first group of DCIs, one of the size of the DCI ofthe first group and the size of a selected DCI of the second group ofDCIs with the other based on said rule, if the size of the DCI of thefirst group is different from the size of each DCI of the second groupof DCIs, wherein the selected DCI of the second group is a DCI whosesize is closest to the size of the DCI of the first group among DCIs ofthe second group having sizes larger than the size of the DCI of thefirst group or a DCI whose size is closest to the size of the DCI of thefirst group among DCIs of the second group having sizes smaller than thesize of the DCI of the first group.

In a third general aspect of the present disclosure, there is provided awireless communication method for a base station, comprising: aligning,for each DCI (Downlink Control Information) of a first group of DCIs,one of the size of the DCI of the first group and the size of a selectedDCI of a second group of DCIs with the other, if the size of the DCI ofthe first group is different from the size of each DCI of the secondgroup of DCIs, wherein the selected DCI of the second group is a DCIwhose size is closest to the size of the DCI of the first group amongDCIs of the second group having sizes larger than the size of the DCI ofthe first group or a DCI whose size is closest to the size of the DCI ofthe first group among DCIs of the second group having sizes smaller thanthe size of the DCI of the first group; and transmitting the first groupof DCIs and the second group of DCIs after the size alignment to a userequipment, wherein the size alignment is based on a rule which is knownby the base station and the user equipment beforehand.

It should be noted that general or specific embodiments may beimplemented as a system, a method, an integrated circuit, a computerprogram, a storage medium, or any selective combination thereof.

Additional benefits and advantages of the disclosed embodiments willbecome apparent from the specification and drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the specification and drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

BRIEF DESCRIPTION OF DRAWINGS

The foregoing and other features of the present disclosure will becomemore fully apparent from the following description and appended claims,taken in conjunction with the accompanying drawings. Understanding thatthese drawings depict only several embodiments in accordance with thedisclosure and are, therefore, not to be considered limiting of itsscope, the disclosure will be described with additional specificity anddetail through use of the accompanying drawings, in which:

FIG. 1 schematically shows an exemplary scenario in which sidelinkresources are dynamically scheduled by an eNodeB for V2V communication;

FIG. 2 illustrates a flowchart of a wireless communication method for abase station according to an embodiment of the present disclosure;

FIG. 3 illustrates a flowchart of a wireless communication method for auser equipment according to another embodiment of the presentdisclosure;

FIG. 4 illustrates a block diagram of a base station according to afurther embodiment of the present disclosure; and; and

FIG. 5 illustrates a block diagram of a user equipment according toanother embodiment of the present disclosure.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form a part thereof. In the drawings,similar symbols typically identify similar components, unless contextdictates otherwise. It will be readily understood that the aspects ofthe present disclosure can be arranged, substituted, combined, anddesigned in a wide variety of different configurations, all of which areexplicitly contemplated and make part of this disclosure.

As described above, sidelink SPS and the dedicated DCI format thereof,which is also referred to be as sidelink SPS DCI format, are underdiscussion in 3GPP. Specifically, two additional fields are suggested tobe added to the sidelink DCI format which is used for dynamic schedulingof V2V/V2X (Vehicle to anything) traffic. In the following, Table 1shows detailed design of the suggested sidlink SPS DCI format withrespect to different bandwidths of carries to be scheduled. Here theassumption is SL SPS configuration index is 3 bits andActivation/release indication is 1 bit based on working assumption in3GPP but in the end the size of these fields may be modified.

TABLE 1 The design of sidelink SPS DCI format Bandwith 1.4 3 5 10 15 20MHz MHz MHz MHz MHz MHz Carrier indicator 3 3 3 3 3 3 Lowest index ofthe 0 2 3 4 4 5 subchannel allocation Frequency resource 0 3 4 6 7 8location Time gap between 4 4 4 4 4 4 initial transmission andretransmission SL SPS configuration 3 3 3 3 3 3 index Activation/release1 1 1 1 1 1 indication Total payload size [bit] 11 16 18 21 22 24Assumption on subchannel 6 5 5 5 5 5 size in terms of PRB

In Table 1, the first four table cells in the first column indicatecontents (i.e. fields) contained in the existing sidelink DCI formatused for dynamic scheduling based on 3GPP TS 36.312. Specifically, thesecontents are “Carrier indicator”, “Lowest index of the subchannelallocation”, “Frequency resource location” and “Time gap between initialtransmission and retransmission”. For different bandwidths of carriersto be scheduled, sizes of some of these fields are different and sizesof others of these fields are the same. For example, Table 1 shows sixdifferent bandwidths, that is, 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz, 20MHz. The size of “Carrier indicator” is 3 bits for all of these sixbandwidths, and the size of “Time gap between initial transmission andretransmission” is 4 bits for all of these six bandwidths. In contrast,the sizes of “Lowest index of the subchannel allocation” are 0 bits, 2bits, 3 bits, 4 bits, 4 bits and 5 bits for bandwidths of 1.4 MHz, 3MHz, 5 MHz, 10 MHz, 15 MHz and 20 MHz respectively. Also, the size of“Frequency resource location” changes per bandwidth of the carrier to bescheduled as shown in Table 1.

In Table 1, the fifth and sixth table cells in the first column indicatethe suggested two additional fields for sidelink (SL) SPS as describedabove. Specifically, these two additional fields are “SL SPSconfiguration index” and “Activation/release indication”. They both areassumed to have fixed sizes (3 bits and 1 bit respectively) fordifferent bandwidths of carriers to be scheduled.

The last two rows in Table 1 respectively shows the total payloads sizes(i.e. the total number of bits) and assumed subchannel sizes (i.e. thenumber of PRBs (Physical Resource Blocks)) of the designed sidelink SPSDCI format for different bandwidths of carriers to be scheduled.Apparently, due to the two additional fields, the total payload size ofthe sidelink SPS DCI will be larger than that of sidelink DCI fordynamical scheduling.

Although the above description is made by taking V2V/V2X communication,a vehicle may also be understood as a UE. That is to say, the directcommunication between two UEs is performed via sidelink between them andmay be scheduled by a base station/eNodeB through the sidelink DCI asdescribed above. Simultaneously, there may be communication between theUE and the eNodeB and such communication is generally scheduled by theeNodeB via conventional DCI format such as DCI format 0, DCI format 1Aand so on. For the purpose of explanation, these DCIs for schedulingtransmission between the UE and the eNodeB are referred to be as Uu(User Equipment to Radio Network System) DCIs.

Since for a UE, sidelink communication with another UE anduplink/downlink communication with the eNodeB may both occurs, in a samesearch space, sidelink DCIs and Uu DCIs as described above may appearsimultaneously and need to be blindly detected/decoded at the UE side.In this case, if the size of a sidelink DCI is different from each of UuDCIs, the blind detection/decoding times at the UE side will beincreased due to introducing SL DCIs. For example, Table 2 showscontents and DCI size of DCI format 0 with respect to differentbandwidths of carriers to be scheduled.

TABLE 2 Contents and DCI size of DCI format 0 Bandwidth 1.4 3 5 10 15 20MHz MHz MHz MHz MHz MHz Carrier indicator 3 3 3 3 3 3 Flag forformat0/format1A 1 1 1 1 1 1 differentiation Hopping flag/RA Type 1 1 11 1 1 1 MSB Resource block assignment 5 7 9 11 12 13 and hoppingresource allocation Modulation and coding 5 5 5 5 5 5 scheme andredundancy version New data indicator 1 1 1 1 1 1 TPC command forscheduled 2 2 2 2 2 2 PUSCH Cyclic shift for DM RS 3 3 3 3 3 3 and OCCindex UL index or Downlink 0 0 0 0 0 0 Assignment Index (DAI) CSIrequest 1 1 1 1 1 1 SRS request 0 0 0 0 0 0 Resource allocation type 1 11 1 1 1 Total payload size [bit] 23 25 27 29 30 31

Here, since fields contained in DCI format 0 and their respective sizesare well known for those skilled in the art, the details thereof isomitted for avoiding confusion of the inventive point of the presentdisclosure. In Table 2, the last row shows total payload sizes of DCIformat 0 are 23 bits, 25 bits, 27 bits, 29 bits, 30 bits and 31 bits fordifferent bandwidths of 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz and 20 MHzrespectively.

Although not shown in Table 1, it can be derived from contents given inTable 1 that total payload sizes of sidelink DCI format for dynamicalscheduling are 7 bits, 12 bits, 14 bits, 17 bits, 18 bits and 20 bitsfor different bandwidths of 1.4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz and 20MHz respectively. By comparison between DCI format 0 and the sidelinkDCI format for dynamical scheduling, it can be seen that the size of thesidelink DCI format for dynamical scheduling is smaller than that of DCIformat 0. Thus, based on the current specification and agreement, zerobits are padded to the sidelink DCI format for dynamical scheduling soas to align the size thereof to that of DCI format 0. Thereby, blinddetection (decoding) times at UE side can be reduced.

However, as described above, due to two additional fields as shown inTable 1, the total payload size of the sidelink SPS DCI will be largerthan that of sidelink DCI for dynamical scheduling by for example 4 bitsfor each bandwidth as shown in Table 1. Thus, by comparison between DCIformat 0 and the sidelink SPS DCI format, there is possibility that thesize of sidelink SPS DCI format is larger than that of DCI format 0. Forthe purpose of understanding easily, Table 3 shows size comparisonbetween SL SPS DCI and DCI format 0.

TABLE 3 size comparison between SL SPS DCI and DCI format 0 Bandwidthfor PCI format 0 1.4 3 5 10 15 20 SL SPS DCI\DCI format 0 MHz MHz MHzMHz MHz MHz Bandwidth 1.4 MHz 11\23 11\25 11\27 11\29 11\30 11\31 for SL3 MHz 16\23 16\25 16\27 16\29 16\30 16\31 SPS DCI 5 MHz 18\23 18\2518\27 18\29 18\30 18\31 10 MHz 21\23 21\25 21\27 21\29 21\30 21\31 15MHz 22\23 22\25 22\27 22\29 22\30 22\31 20 MHz 24\23 24\25 24\27 24\2924\30 24\31

As shown in Table 3, in each table cell containing two numbers, thenumber at left side of “\” indicates the size (total payload size) of SLSPS DCI for a certain bandwidth of carrier to be scheduled, and thenumber at right side of “\” indicates the size (total payload size) ofDCI format 0 for the certain bandwidth of carrier to be scheduled. Itcan be seen from Table 3 that in a case that SL SPS DCI is used toschedule a carrier of bandwidth of 20 MHz and DCI format 0 is used toschedule a carrier of bandwidth of 1.4 MHz, the size (24 bits) of SL SPSDCI is larger than the size (23 bits) of DCI format 0, as shown in thetable cell “24/23”. Since the current specification and agreement onlyconsider the case that the size of the sidelink DCI format for dynamicalscheduling is smaller than that of DCI format 0, UE behavior is unclearwhen the size of SL SPS DCI is larger than the size of DCI format 0.

Furthermore, in LTE (Long Term Evolution), it is known that DCI format 0and DCI format 1A (as well as format 3/3A) are padded to each other inorder for size alignment. However, DCI format 0 and DCI format 1A areonly related to size alignment between two DCIs. Until now, it isunclear how to handle the size alignment in cases that there are morethan two DCIs including at least one sidelink DCI and at least one UuDCI. For example, the size of a sidelink DCI may be smaller than that ofone Uu DCI but larger than that of another Uu DCI.

In addition, in NR (New Radio access technology) or 5G (The fifthGeneration) system, sidelink DCIs and Uu DCIs may also appear in a samesearch space similarly as in cases described above, and how to implementthe size alignment between DCIs needs to be considered too.

In an embodiment of the present disclosure, there is provided a wirelesscommunication method 20 for a base station as shown in FIG. 2. FIG. 2illustrates a flowchart of a wireless communication method 20 for a basestation according to an embodiment of the present disclosure.

As shown in FIG. 2, the wireless communication method 20 starts at stepS201 in which, for each DCI of a first group of DCIs, one of the size ofthe DCI of the first group and the size of a selected DCI of a secondgroup of DCIs is aligned with the other, if the size of the DCI of thefirst group is different from the size of each DCI of the second groupof DCIs, wherein the selected DCI of the second group is a DCI whosesize is closest to the size of the DCI of the first group among DCIs ofthe second group having sizes larger than the size of the DCI of thefirst group or a DCI whose size is closest to the size of the DCI of thefirst group among DCIs of the second group having sizes smaller than thesize of the DCI of the first group. Then, at step S202, the first groupof DCIs and the second group of DCIs after the size alignment aretransmitted to a user equipment. After step S202, the wirelesscommunication method 20 ends. The size alignment is based on a rulewhich is known by the base station and the user equipment beforehand.

Specifically, for example, the base station may be eNodeB 101 as shownin FIG. 1 and the user equipment may be any one of vehicles 102 and 103as shown in FIG. 1. That is to say, the wireless communication method 20may be used by eNodeB 101 to schedule sidelink transmission and/orreception as well as uplink transmission and downlink reception ofvehicles 102 and 103.

For the purpose of explanation, it may be assumed that the first groupof DCIs are DCIs for scheduling sidelink transmission between the userequipment and another user equipment and that the second group of DCIsare DCIs for scheduling transmission between the user equipment and thebase station. As described above, the first group of DCIs may bereferred simply to be as SL DCIs and the second group of DCIs may bereferred simply to be as Uu DCIs.

As described above, in a same search space, there may be at least one SLDCI and at least one Uu DCI and the size of the SL DCI may be smaller orlarger than the Uu DCI in one case. In another case, in a same searchspace, there may be more than one SL DCIs and more than one Uu DCIs andthe size relationship between the SL DCIs and Uu DCIs may be verycomplicated. If no size alignment of these DCIs is performed, there willbe many kinds of sizes of DCIs, blind detection of these DCIs needs tobe performed too many times at the user equipment in order to correctlydetect these DCIs, which will result in time consuming and system loadincreasing.

At step S201, for each SL DCI, if the size of the SL DCI is differentfrom that of each Uu DCI, the size alignment is performed between the SLDCI and an Uu DCI whose size is smallest among Uu DCIs having sizeslarger than the SL DCI or an Uu DCI whose size is largest among Uu DCIshaving sizes smaller than the SL DCI. Thus, firstly, the blind detectiontimes at UE side can be reduced. Secondly, since the selected Uu DCI isan Uu DCI whose size is smallest among Uu DCIs having sizes larger thanthe SL DCI or an Uu DCI whose size is largest among Uu DCIs having sizessmaller than the SL DCI, the minimum size change of DCIs can be kept.

In addition, since the rule on which the size alignment is based isknown by the base station and the user equipment beforehand, UE mayblindly detect these DCIs after the size alignment by the base stationbased on the rule. The rule may be predefined in a standard.Alternatively, the rule may also be defined by the base station, and thebase station needs to notify UE of the rule for example via upper-layersignaling before UE performs the blind detection of DCIs. Apparently,the definition manner of the rule may also be any other suitable mannerand the present disclosure is not limited to the above two manners.

When there are more than one SL DCIs and more than one Uu DCIs,different SL DCIs may be aligned with different Uu DCIs. Specificexamples of the size alignment between SL DCIs and Uu DCIs will befurther given later for facilitating understanding the wirelesscommunication method 20.

With the wireless communication method 20, by performing the sizealignment between each DCI of the first group of DCIs and the selectedDCI of the second group whose size is closest to that of the each DCI ofthe first group, blind detection times at the user equipment can bereduced while minimizing the size change of DCIs.

According to an embodiment of the present disclosure, in the wirelesscommunication method 20 as shown in FIG. 2, the selected DCI of thesecond group is a DCI whose size is closest to the size of the DCI ofthe first group among DCIs of the second group having sizes larger thanthe size of the DCI of the first group. And, although not shown in FIG.2, in step S201, aligning one of the size of the DCI of the first groupand the size of the selected DCI of a second group of DCIs with theother may comprises a sub-step of increasing bits in the DCI of thefirst group, wherein the number of the increased bits equals to thedifference between the size of the DCI of the first group and that ofthe selected DCI of the second group.

Specifically, in a first example, it is assumed that a UE is configuredwith TM (Transmission Mode) 10 and is expected to decode DCI format 0and DCI format 2D for an Uu channel of bandwidth of 1.4 MHz and todecode SL SPS DCI for a sidelink channel of bandwidth of 20 MHz. That isto say, the first group of DCIs includes only one SL DCI, that is, SLSPS DCI as shown in Table 1, and the second group of DCIs includes twoUu DCIs, that is, DCI format 0 as shown in Table 2 and DCI format 2D.Table 4 shows the design (contents/fields and size) of DCI format 2D forthe bandwidth of 1.4 MHz.

TABLE 4 The design of DCI format 2D Field Size Total Payload Size FieldName [bit] [bit] Carrier indicator 3 35 Resource allocation header 0Resource block assignment 6 TPC command for PUCCH 2 Downlink AssignmentIndex 0 HARQ process number 3 Antenna port(s), scrambling 3 identity andnumber of layers SRS request 0 TB1 Modulation and coding scheme 5 TB1New data indicator 1 TB1 Redundancy version 2 TB2 Modulation and codingscheme 5 TB2 New data indicator 1 TB2 Redundancy version 2 PDSCH REMapping and Quasi- 2 Co-Location Indicator HARQ-ACK resource offset 0

Based on Table 1, the size of SL SPS DCI is 24 bits for the bandwidth of20 MHz. Based on Table 2, the size of DCI format 0 is 23 bits for thebandwidth of 1.4 MHz. In addition, based on Table 4, the size of DCIformat 2D is 35 bits for the bandwidth of 1.4 MHz. Since DCI format 2Dis well known by those skilled in the art, the detailed design thereoffor other bandwidths will not be given here for avoiding confusion ofthe inventive point of the present disclosure. In this case, the size ofSL SPS DCI is larger than that of DCI format 0 and smaller than that ofDCI format 2D. It is possible to increase bits in SL SPS DCI by 11 bitsto align the size of SL SPS DCI with that of DCI format 2D. Thereby,blind detection times at UE side are not increased due to introducingSPS SL DCI, meanwhile the two Uu DCIs (DCI format 0 and DCI format 2D)are not impacted in all respects of size, content and coverage.

By increasing bits in the DCI of the first group to align the size ofthe DCI of the first group with the selected DCI of the second group,blind detection times at the user equipment can be reduced withoutimpacting the second group of DCIs.

According to an embodiment of the present disclosure, in the wirelesscommunication method 20 as shown in FIG. 2, although not shown in FIG.2, the above sub-step may comprise: padding bits to the DCI of the firstgroup or increasing CRC (Cyclic Redundancy Check) size in the DCI of thefirst group.

Specifically, in the first example, SL SPS DCI may be padded with 11 “0”bits to align with DCI format 2D. It is noted that the padded bits arenot limited to “0”, and may be “1” or any other suitable bits.

Alternatively, it is also possible to increase CRC size in SL SPS DCI by11 bits to align with DCI format 2D. In this case, by increasing CRCsize, the accuracy and integrity of data transmission will be furtherimproved while reducing blind detection times at UE side.

It is noted that, the above manners of increasing bits in the DCI of thefirst group so as to align with the selected DCI of the second group areonly examples, the present disclosure is not limited thereto, and thoseskilled in the art may employ any other suitable manners.

According to an embodiment of the present disclosure, in the wirelesscommunication method 20 as shown in FIG. 2, the selected DCI of thesecond group is a DCI whose size is closest to the size of the DCI ofthe first group among DCIs of the second group having sizes smaller thanthe size of the DCI of the first group. And, although not shown in FIG.2, in step S201, aligning one of the size of the DCI of the first groupand the size of the selected DCI of a second group of DCIs with theother may comprises a sub-step of reducing bits in the DCI of the firstgroup, wherein the number of the reduced bits equals to the differencebetween the size of the DCI of the first group and that of the selectedDCI of the second group.

For convenience of understanding, the above first example is still takenas an example. Although the size of SL SPS DCI is aligned with that ofDCI format 2D in the above description, the present disclosure is notlimited thereto. It is also possible to align the size of SL SPS DCIwith that of DCI format 0 by reducing 1 bit in SL SPS DCI. Similarly,blind detection times at UE side are not increased due to introducingSPS SL DCI, meanwhile the two Uu DCIs (DCI format 0 and DCI format 2D)are not impacted in all respects of size, content and coverage.

Thus, by reducing bits in the DCI of the first group to align the sizeof the DCI of the first group with the selected DCI of the second group,blind detection times at the user equipment can be reduced withoutimpacting the second group of DCIs.

According to an embodiment of the present disclosure, in the wirelesscommunication method 20 as shown in FIG. 2, although not shown in FIG.2, the above sub-step may comprise: restricting the number of bits in atleast one field in the DCI of the first group or by increasing thegranularity of resource allocation in the DCI of the first group.

Specifically, it is possible to specify, for example in a standard, somerestriction on field usage in SL DCI for some special case, for example,when SL refers to a larger bandwidth such as 20 MHz and Uu refers to asmaller bandwidth such as 1.4 MHz. More specifically, in the firstexample, since SL SPS DCI refers to sidelink channel of bandwidth of 20MHz and two Uu DCIs refer to Uu channel of bandwidth of 1.4 MHz, it canbe specified that the field of “SPS configuration index” in SL SPS DCIis squeezed to 2 bits from the default 3 bits as shown in Table 1.Thereby, the total payload size of SL SPS DCI can be reduced to be 23bits which is equivalent to that of DCI format 0.

Alternatively, since the larger the granularity of resource allocationin DCI, the smaller the size of the DCI, the granularity of resourceallocation in SL SPS DCI may be increased to reduce 1 bit in SL SPS DCI.More specifically, the configured sub-channel size should be larger than6 PRBs for SL SPS DCI in the first example for example.

It is noted that, the above manners of reducing bits in the DCI of thefirst group so as to align with the selected DCI of the second group areonly examples, the present disclosure is not limited thereto, and thoseskilled in the art may employ any other suitable manners.

The above first example only gives a simple case in which there is onlyone SL DCI. In the following, a more complicated case is given by asecond example. In the second example, it is assumed that a UE is toreceive two Uu uplink DCIs in which one is used for CP-OFDM (CyclicPrefix-Orthogonal Frequency Division Multiplexing) based uplinktransmission and the other is used for DFT-S-OFDM (Discrete FourierTransform-Spread-OFDM) based uplink transmission. And, the UE is alsoassumed to receive two SL DCIs in which one is used for dynamicscheduling and the other is used for SL SPS.

In order for convenience of explanation, the two Uu DCIs are representedby DCI1_uu and DCI2_uu and the two SL DCIs are indicated by DCI3_SL andDCI4_SL. In addition, the size relation of these four DCIs can beexpressed as DCI1_uu >DCI4_SL>DCI2_uu>DCI3_SL. In this case, based onthe wireless communication method 40 shown in FIG. 2, one option is toalign the size of DCI4_SL with that of DCI1_uu by for example paddingbits to DCI4_SL and to align the size of DCI3_SL with that of DCI2_uu byfor example padding bits to DCI3_SL. Thereby, as described above,different SL DCIs are aligned with different Uu DCIs.

It is known that padding more bits will result in increased overhead andincreased error rate. Since DCI4_SL is aligned with its smallest largerUu DCI (i.e. DCI1_uu) meanwhile DCI3_SL is aligned with its smallestlarger Uu DCI (i.e. DCI2_uu), minimum bits padded to each SL DCI can bekept. Thereby, the size increase of SL DCIs is minimized. Meanwhile,blind detection times at UE side are also not changed compared with thecase without SL DCIs.

Similarly with the first example, in the second example, the anotheroption may be to align DCI4_SL with that of its largest smaller Uu DCI(i.e. DCI2_uu) by reducing bits in DCI4_SL and to align the size ofDCI3_SL with that of its smallest larger Uu DCI (i.e. DCI2_uu) byincreasing bits in DCI3_SL.

In the above first and second examples, the size of SL DCI is alignedwith that of Uu DCI by either increasing or reducing bits in SL DCI.However, the present disclosure is not limited thereto. In NR/5G cases,it is also possible to align the size of Uu DCI with that of SL DCI.

According to an embodiment of the present disclosure, in the wirelesscommunication method 20 as shown in FIG. 2, the selected DCI of thesecond group is a DCI whose size is closest to the size of the DCI ofthe first group among DCIs of the second group having sizes smaller thanthe size of the DCI of the first group. And, although not shown in FIG.2, in step S201, aligning one of the size of the DCI of the first groupand the size of the selected DCI of a second group of DCIs with theother may comprises a sub-step of adding bits to the selected DCI of thesecond group, wherein the number of the added bits equals to thedifference between the size of the DCI of the first group and that ofthe selected DCI of the second group.

For convenience of understanding, the description is made based on athird example. In the third example, it is assumed that a UE is toreceive two Uu DCIs in which one is TM specific DCI and the other isfallback DCI. And, the UE is also assumed to receive two SL DCIs inwhich one is used for dynamic scheduling and the other is used for SLSPS.

In order to convenience of explanation, as in the second example, thetwo Uu DCIs are also represented by DCI1_uu and DCI2_uu and the two SLDCIs are also indicated by DCI3_SL and DCI4_SL. Different from thesecond example, in the third example, the size relation of these fourDCIs can be expressed as DCI4_SL>DCI3_SL>DCI1_uu>DCI2_uu. In this case,based on the above sub-step, firstly, for DCI4_SL, since DCI1_uu is thelargest smaller Uu DCI, it is possible to align the size of DCI1_uu withthat of DCI4_SL by adding bits to DCI1_uu, which is different from theabove first and second examples. Secondly, for DCI3_SL, since DCI1_uu isalso the largest smaller Uu DCI, the size alignment should also beperformed between DCI3_SL and DCI1_uu, which is equivalent to that thesize of DCI3_SL is aligned with that of DCI4_SL by increasing bits inDCI3_SL. In summary, both the size of DCI1_uu and the size of DCI3_SLare aligned with that of DCI4_SL. Thereby, the fallback DCI (DCI2_uu)keeps unchanged, that is to say, the content, size and coverage thereofis kept. Meanwhile, by aligning both the size of DCI1_uu and the size ofDCI3_SL with that of DCI4_SL, blind detection times at UE side can bereduced.

Alternatively, another option for the third example may be aligning thesizes of all of DCI3_SL, DCI1_uu and DCI2_uu with that of DCI4_SL. Inthis case, the blind detection times at UE side may be smallest.

Based on the third example, it can be seen that all of Uu DCIs or atleast TM specific Uu DCIs is aligned in size with the largest SL DCI ifnone of Uu DCIs has larger size than that of any SL DCI. However, thisis only two possible manner of size alignment of DCIs, the presentdisclosure is not limited thereto, and those skilled in the art mayemploy any other suitable manner size alignment of DCIs. For example,both the size of DCI1_uu and the size of DCI2_uu or only the size ofDCI1_uu may be aligned with DCI3_SL by adding bits thereto, meanwhilethe size of DCI4_SL may be aligned with that of DCI3_SL by reducing bitsin DCI4_SL.

Thus, by adding bits to the selected DCI of the second group to alignthe size of the selected DCI of the second group with the DCI of thefirst group, blind detection times at the user equipment can be reduced.

According to an embodiment of the present disclosure, in the wirelesscommunication method 20 as shown in FIG. 2, although not shown in FIG.2, the above sub-step may comprise: padding bits to the selected DCI ofthe second group or increasing the number of bits in at least one fieldin the selected DCI.

For example, in the third example, it is possible to pad bits such as“0”, “1” or any other bits to DCI1_uu so as to align the size of DCI1_uuwith that of DCI4_uu. Also, for the another option as described above,it is possible to pad bits such as “0”, “1” or any other bits to DCI2_uuso as to align the size of DCI2_uu with that of DCI4_uu.

Alternatively, as for SL DCI, it is also possible to specify, forexample in a standard, some restriction on field usage in Uu DCI forsome special case, for example, when SL refers to larger bandwidth suchas 20 MHz and Uu refers to smaller bandwidth such as 1.4 MHz. Morespecifically, it can be specified that only 2 or 3 bits instead ofdefault 1 bit can be configured for the field of “CSI request” in thiscase. Thereby, the number of bits in Uu DCI may be increased. Also,similarly with SL DCI, it is also possible to increase CRC size in UuDCI so as to add bits to Uu DCI.

Furthermore, a fourth example as an extension to the first example and ageneral case is further described below for facilitating understandingof the present disclosure. In the fourth example, a UE is assumed toreceive at least two Uu DCIs represented as DCI1_uu and DCI2_uu, and toreceive at least one SL DCI indicated by DCI3_SL. there are at leastthree possible size relations among these three DCIs. The first sizerelation is assumed to be DCI1_uu>DCI3_SL>DCI2_uu, which corresponds tothe case in the first example for instance. In this case, as describedabove, one option is to align the size of DCI3_SL with that of DCI1_uuby increasing bits in DCI3_SL. Another option is to align the size ofDCI3_SL with that of DCI2_uu by reducing bits in DCI3_SL. A furtheroption is to align the size of DCI2_uu with that of DCI3_SL by addingbits to DCI2_uu.

The second size relation is assumed to be DCI1_uu>DCI2_uu>DCI3_SL. Inthis case, the size of DCI3_SL is aligned with that of DCI2_uu byincreasing bits in DCI3_SL.

The third size relation is assumed to be DCI3_SL>DCI1_uu>DCI2_uu. Inthis case, one option is to align the size of DCI1_uu with that ofDCI3_SL by adding bits to DCI1_uu. Another option is to align the sizeof DCI3_SL with that of DCI1_uu by reducing bits in DCI3_SL. For the oneoption, it is also possible to further align the size of DCI2_uu withthat of DCI3_SL by adding bits to DCI2_uu, which will results insmallest times of blind detection at UE side.

It is noted that, although SL DCIs and Uu DCIs are described in theabove examples, the present disclosure is not limited thereto, the firstgroup of DCIs can be other types of DCIs than SL DCIs and the secondgroup of DCIs can be other types of DCIs than Uu DCIs. Also, althoughnot given in the above, the selected DCI of the second group may also bealigned with that of the DCI of the first group by reducing bitsdepending on specific cases.

In the above, the wireless communication method 20 is described indetail with reference to FIGS. 1-2. With the wireless communicationmethod 20, by performing the size alignment between each DCI of thefirst group of DCIs and the selected DCI of the second group whose sizeis closest to that of the each DCI of the first group, blind detectiontimes at the user equipment can be reduced while minimizing the sizechange of DCIs.

In another embodiment of the present disclosure, there is provided awireless communication method 30 for a user equipment as shown in FIG.3. FIG. 3 illustrates a flowchart of a wireless communication method 30for a user equipment according to another embodiment of the presentdisclosure.

As shown in FIG. 3, the wireless communication method 30 starts at stepS301 in which a first group of DCIs and a second group of DCIs isreceived from a base station. Then, at step S302, the first group ofDCIs and the second group of DCIs is detected blindly so as to performtransmission and/or reception based on a rule which is known by the basestation and the user equipment beforehand. After step S702, the wirelesscommunication method 30 ends. Said rule indicates that before beingreceived by the user equipment, the first group of DCIs and the secondgroup of DCIs has been subject to size alignment comprising: aligning,for each DCI of the first group of DCIs, one of the size of the DCI ofthe first group and the size of a selected DCI of the second group ofDCIs with the other based on said rule, if the size of the DCI of thefirst group is different from the size of each DCI of the second groupof DCIs, wherein the selected DCI of the second group is a DCI whosesize is closest to the size of the DCI of the first group among DCIs ofthe second group having sizes larger than the size of the DCI of thefirst group or a DCI whose size is closest to the size of the DCI of thefirst group among DCIs of the second group having sizes smaller than thesize of the DCI of the first group. For example, the wirelesscommunication method 30 may be applied to vehicles 102 and 130 as shownin FIG. 1.

According to an embodiment of the present disclosure, in the wirelesscommunication method 30 as shown in FIG. 3, the selected DCI of thesecond group is a DCI whose size is closest to the size of the DCI ofthe first group among DCIs of the second group having sizes larger thanthe size of the DCI of the first group, and said aligning one of thesize of the DCI of the first group and the size of the selected DCI of asecond group of DCIs with the other comprises: increasing bits in theDCI of the first group, and the number of the increased bits equals tothe difference between the size of the DCI of the first group and thatof the selected DCI of the second group.

According to an embodiment of the present disclosure, in the wirelesscommunication method 30 as shown in FIG. 3, said increasing bits in theDCI of the first group comprises: padding bits to the DCI of the firstgroup or increasing CRC size in the DCI of the first group.

According to an embodiment of the present disclosure, in the wirelesscommunication method 30 as shown in FIG. 3, the selected DCI of thesecond group is a DCI whose size is closest to the size of the DCI ofthe first group among DCIs of the second group having sizes smaller thanthe size of the DCI of the first group, and said aligning one of thesize of the DCI of the first group and the size of the selected DCI of asecond group of DCIs with the other comprises: reducing bits in the DCIof the first group, and the number of the reduced bits equals to thedifference between the size of the DCI of the first group and that ofthe selected DCI of the second group.

According to an embodiment of the present disclosure, in the wirelesscommunication method 30 as shown in FIG. 3, said reducing bits in theDCI of the first group comprises: restricting the number of bits in atleast one field in the DCI of the first group or increasing thegranularity of resource allocation in the DCI of the first group.

According to an embodiment of the present disclosure, in the wirelesscommunication method 30 as shown in FIG. 3, the selected DCI of thesecond group is a DCI whose size is closest to the size of the DCI ofthe first group among DCIs of the second group having sizes smaller thanthe size of the DCI of the first group, and said aligning one of thesize of the DCI of the first group and the size of the selected DCI of asecond group of DCIs with the other comprises: adding bits to theselected DCI of the second group, wherein the number of the added bitsequals to the difference between the size of the DCI of the first groupand that of the selected DCI of the second group.

According to an embodiment of the present disclosure, in the wirelesscommunication method 30 as shown in FIG. 3, said adding bits to theselected DCI of the second group comprising: padding bits to theselected DCI of the second group or increasing the number of bits in atleast one field in the selected DCI.

According to an embodiment of the present disclosure, in the wirelesscommunication method 30 as shown in FIG. 3, the first group of DCIs areDCIs for scheduling sidelink transmission between the user equipment andanother user equipment, and the second group of DCIs are DCIs forscheduling transmission between the user equipment and the base station.

With the wireless communication method 30, by performing the sizealignment between each DCI of the first group of DCIs and the selectedDCI of the second group whose size is closest to that of the each DCI ofthe first group, blind detection times at the user equipment can bereduced while minimizing the size change of DCIs.

In a further embodiment of the present disclosure, there is provided abase station 400 as shown in FIG. 4. FIG. 4 illustrates a block diagramof a base station 400 according to a further embodiment of the presentdisclosure.

As shown in FIG. 4, the base station 400 includes: a circuitry 401operative to align, for each DCI (Downlink Control Information) of afirst group of DCIs, one of the size of the DCI of the first group andthe size of a selected DCI of a second group of DCIs with the other, ifthe size of the DCI of the first group is different from the size ofeach DCI of the second group of DCIs, wherein the selected DCI of thesecond group is a DCI whose size is closest to the size of the DCI ofthe first group among DCIs of the second group having sizes larger thanthe size of the DCI of the first group or a DCI whose size is closest tothe size of the DCI of the first group among DCIs of the second grouphaving sizes smaller than the size of the DCI of the first group; and atransmitter 402 operative to transmit the first group of DCIs and thesecond group of DCIs after the size alignment by the circuitry to a userequipment. The size alignment is based on a rule which is known by thebase station and the user equipment beforehand.

The base station 400 according to the present embodiment may furtherinclude a CPU (Central Processing Unit) 410 for executing relatedprograms to process various data and control operations of respectiveunits in the base station 400, a ROM (Read Only Memory) 8413 for storingvarious programs required for performing various process and control bythe CPU 410, a RAM (Random Access Memory) 415 for storing intermediatedata temporarily produced in the procedure of process and control by theCPU 410, and/or a storage unit 417 for storing various programs, dataand so on. The above circuitry 401, transmitter 402, CPU 410, ROM 413,RAM 415 and/or storage unit 417 etc. may be interconnected via dataand/or command bus 420 and transfer signals between one another.

Respective units as described above do not limit the scope of thepresent disclosure. According to one embodiment of the disclosure, thefunctions of the above circuitry 401 and transmitter 402 may beimplemented by hardware, and the above CPU 410, ROM 413, RAM 415 and/orstorage unit 417 may not be necessary. Alternatively, part or all offunctions of the above circuitry 401 or transmitter 402 may also beimplemented by functional software in combination with the above CPU410, ROM 413, RAM 415 and/or storage unit 417 etc.

Specifically, the base station 400 may be eNodeB 101 shown in FIG. 1 andmay perform the wireless communication method 20 as described above inconjunction with FIG. 2.

With the base station 400, by performing the size alignment between eachDCI of the first group of DCIs and the selected DCI of the second groupwhose size is closest to that of the each DCI of the first group, blinddetection times at the user equipment can be reduced while minimizingthe size change of DCIs.

Note that, the other technical features in the above wirelesscommunication method 20 can also be incorporated in the base station 400and will not be described here for avoid redundancy.

In another embodiment of the present disclosure, there is provided auser equipment 500 as shown in FIG. 5. FIG. 5 illustrates a blockdiagram of a user equipment 500 according to another embodiment of thepresent disclosure.

As shown in FIG. 5, the user equipment 500 includes: a receiver 501operative to receive a first group of DCIs and a second group of DCIsfrom a base station; and a circuitry 302 operative to blindly detect thefirst group of DCIs and the second group of DCIs so as to performtransmission and/or reception based on a rule which is known by the basestation and the user equipment beforehand. And, said rule indicates thatbefore being received by the user equipment, the first group of DCIs andthe second group of DCIs has been subject to size alignment comprising:aligning, for each DCI of the first group of DCIs, one of the size ofthe DCI of the first group and the size of a selected DCI of the secondgroup of DCIs with the other based on said rule, if the size of the DCIof the first group is different from the size of each DCI of the secondgroup of DCIs, wherein the selected DCI of the second group is a DCIwhose size is closest to the size of the DCI of the first group amongDCIs of the second group having sizes larger than the size of the DCI ofthe first group or a DCI whose size is closest to the size of the DCI ofthe first group among DCIs of the second group having sizes smaller thanthe size of the DCI of the first group.

The user equipment 500 according to the present embodiment may furtherinclude a CPU (Central Processing Unit) 510 for executing relatedprograms to process various data and control operations of respectiveunits in the user equipment 500, a ROM (Read Only Memory) 513 forstoring various programs required for performing various process andcontrol by the CPU 510, a RAM (Random Access Memory) 515 for storingintermediate data temporarily produced in the procedure of process andcontrol by the CPU 510, and/or a storage unit 517 for storing variousprograms, data and so on. The above receiver 501, circuitry 502, CPU510, ROM 513, RAM 515 and/or storage unit 517 etc. may be interconnectedvia data and/or command bus 520 and transfer signals between oneanother.

Respective units as described above do not limit the scope of thepresent disclosure. According to one embodiment of the disclosure, thefunctions of the above receiver 501 and circuitry 502 may be implementedby hardware, and the above CPU 510, ROM 513, RAM 515 and/or storage unit517 may not be necessary. Alternatively, part or all of functions of theabove receiver 501 and/or circuitry 502 may also be implemented byfunctional software in combination with the above CPU 510, ROM 513, RAM515 and/or storage unit 517 etc.

Specifically, the user equipment 500 may be vehicles 102 and 103 shownin FIG. 1 and may perform the wireless communication method 30 asdescribed above in conjunction with FIG. 3.

With the user equipment 500, by performing the size alignment betweeneach DCI of the first group of DCIs and the selected DCI of the secondgroup whose size is closest to that of the each DCI of the first group,blind detection times at the user equipment can be reduced whileminimizing the size change of DCIs.

Note that, the other technical features in the above wirelesscommunication method 30 can also be incorporated in the user equipment500 and will not be described here for avoid redundancy.

The present disclosure can be realized by software, hardware, orsoftware in cooperation with hardware. Each functional block used in thedescription of each embodiment described above can be realized by an LSIas an integrated circuit, and each process described in the eachembodiment may be controlled by LSI. They may be individually formed aschips, or one chip may be formed so as to include a part or all of thefunctional blocks. They may include a data input and output coupledthereto. The LSI here may be referred to as an IC, a system LSI, a superLSI, or an ultra LSI depending on a difference in the degree ofintegration. However, the technique of implementing an integratedcircuit is not limited to the LSI and may be realized by using adedicated circuit or a general-purpose processor. In addition, a FPGA(Field Programmable Gate Array) that can be programmed after themanufacture of the LSI or a reconfigurable processor in which theconnections and the settings of circuits cells disposed inside the LSIcan be reconfigured may be used.

It is noted that the present disclosure intends to be variously changedor modified by those skilled in the art based on the descriptionpresented in the specification and known technologies without departingfrom the content and the scope of the present disclosure, and suchchanges and applications fall within the scope that claimed to beprotected. Furthermore, in a range not departing from the content of thedisclosure, the constituent elements of the above-described embodimentsmay be arbitrarily combined.

Embodiments of the present disclosure can at least provide the followingsubject matters.

(1). A base station, comprising:

circuitry operative to align, for each DCI (Downlink ControlInformation) of a first group of DCIs, one of the size of the DCI of thefirst group and the size of a selected DCI of a second group of DCIswith the other, if the size of the DCI of the first group is differentfrom the size of each DCI of the second group of DCIs, wherein theselected DCI of the second group is a DCI whose size is closest to thesize of the DCI of the first group among DCIs of the second group havingsizes larger than the size of the DCI of the first group or a DCI whosesize is closest to the size of the DCI of the first group among DCIs ofthe second group having sizes smaller than the size of the DCI of thefirst group; and

a transmitter operative to transmit the first group of DCIs and thesecond group of DCIs after the size alignment by the circuitry to a userequipment,

wherein the size alignment is based on a rule which is known by the basestation and the user equipment beforehand.

(2). The base station according to (1), wherein the selected DCI of thesecond group is a DCI whose size is closest to the size of the DCI ofthe first group among DCIs of the second group having sizes larger thanthe size of the DCI of the first group, and

wherein the circuitry further increases bits in the DCI of the firstgroup, and the number of the increased bits equals to the differencebetween the size of the DCI of the first group and that of the selectedDCI of the second group.

(3). The base station according to (2), wherein the circuitry increasesbits in the DCI of the first group by padding bits or increasing CRC(Cyclic Redundancy Check) size.

(4). The base station according to (1), wherein the selected DCI of thesecond group is a DCI whose size is closest to the size of the DCI ofthe first group among DCIs of the second group having sizes smaller thanthe size of the DCI of the first group, and

wherein the circuitry further reduces bits in the DCI of the firstgroup, and the number of the reduced bits equals to the differencebetween the size of the DCI of the first group and that of the selectedDCI of the second group.

(5). The base station according to (4), wherein the circuitry reducesbits in the DCI of the first group by restricting the number of bits inat least one field in the DCI of the first group or by increasing thegranularity of resource allocation in the DCI of the first group.

(6). The base station according to (1), wherein the selected DCI of thesecond group is a DCI whose size is closest to the size of the DCI ofthe first group among DCIs of the second group having sizes smaller thanthe size of the DCI of the first group, and

wherein the circuitry further adds bits to the selected DCI of thesecond group, and the number of the added bits equals to the differencebetween the size of the DCI of the first group and that of the selectedDCI of the second group.

(7). The base station according to (6), wherein the circuitry adds bitsto the selected DCI of the second group by padding bits or by increasingthe number of bits in at least one field in the selected DCI.

(8). The base station according to (1), wherein the first group of DCIsare DCIs for scheduling sidelink transmission between the user equipmentand another user equipment, and the second group of DCIs are DCIs forscheduling transmission between the user equipment and the base station.

(9). A user equipment, comprising:

a receiver operative to receive a first group of DCIs and a second groupof DCIs from a base station; and

a circuitry operative to blindly detect the first group of DCIs and thesecond group of DCIs so as to perform transmission and/or receptionbased on a rule which is known by the base station and the userequipment beforehand,

wherein said rule indicates that before being received by the userequipment, the first group of DCIs and the second group of DCIs has beensubject to size alignment comprising: aligning, for each DCI of thefirst group of DCIs, one of the size of the DCI of the first group andthe size of a selected DCI of the second group of DCIs with the otherbased on said rule, if the size of the DCI of the first group isdifferent from the size of each DCI of the second group of DCIs, whereinthe selected DCI of the second group is a DCI whose size is closest tothe size of the DCI of the first group among DCIs of the second grouphaving sizes larger than the size of the DCI of the first group or a DCIwhose size is closest to the size of the DCI of the first group amongDCIs of the second group having sizes smaller than the size of the DCIof the first group.

(10). The user equipment according to (9), wherein the selected DCI ofthe second group is a DCI whose size is closest to the size of the DCIof the first group among DCIs of the second group having sizes largerthan the size of the DCI of the first group, and

wherein said aligning one of the size of the DCI of the first group andthe size of the selected DCI of a second group of DCIs with the othercomprises:

increasing bits in the DCI of the first group, and the number of theincreased bits equals to the difference between the size of the DCI ofthe first group and that of the selected DCI of the second group.

(11). The user equipment according to (10), wherein said increasing bitsin the DCI of the first group comprises:

padding bits to the DCI of the first group or increasing CRC size in theDCI of the first group.

(12). The user equipment according to (9), wherein the selected DCI ofthe second group is a DCI whose size is closest to the size of the DCIof the first group among DCIs of the second group having sizes smallerthan the size of the DCI of the first group, and

wherein said aligning one of the size of the DCI of the first group andthe size of the selected DCI of a second group of DCIs with the othercomprises:

reducing bits in the DCI of the first group, and the number of thereduced bits equals to the difference between the size of the DCI of thefirst group and that of the selected DCI of the second group.

(13). The user equipment according to (12), wherein said reducing bitsin the DCI of the first group comprises:

restricting the number of bits in at least one field in the DCI of thefirst group or increasing the granularity of resource allocation in theDCI of the first group.

(14). The user equipment according to (9), wherein the selected DCI ofthe second group is a DCI whose size is closest to the size of the DCIof the first group among DCIs of the second group having sizes smallerthan the size of the DCI of the first group, and

wherein said aligning one of the size of the DCI of the first group andthe size of the selected DCI of a second group of DCIs with the othercomprises:

adding bits to the selected DCI of the second group, wherein the numberof the added bits equals to the difference between the size of the DCIof the first group and that of the selected DCI of the second group.

(15). The user equipment according to (14), wherein said adding bits tothe selected DCI of the second group comprising:

padding bits to the selected DCI of the second group or increasing thenumber of bits in at least one field in the selected DCI.

(16). The user equipment according to (9), wherein the first group ofDCIs are DCIs for scheduling sidelink transmission between the userequipment and another user equipment, and the second group of DCIs areDCIs for scheduling transmission between the user equipment and the basestation.

(17). A wireless communication method for a base station, comprising:

aligning, for each DCI (Downlink Control Information) of a first groupof DCIs, one of the size of the DCI of the first group and the size of aselected DCI of a second group of DCIs with the other, if the size ofthe DCI of the first group is different from the size of each DCI of thesecond group of DCIs, wherein the selected DCI of the second group is aDCI whose size is closest to the size of the DCI of the first groupamong DCIs of the second group having sizes larger than the size of theDCI of the first group or a DCI whose size is closest to the size of theDCI of the first group among DCIs of the second group having sizessmaller than the size of the DCI of the first group; and

transmitting the first group of DCIs and the second group of DCIs afterthe size alignment to a user equipment,

wherein the size alignment is based on a rule which is known by the basestation and the user equipment beforehand. (18). The wirelesscommunication method according to (17), wherein the selected DCI of thesecond group is a DCI whose size is closest to the size of the DCI ofthe first group among DCIs of the second group having sizes larger thanthe size of the DCI of the first group, and

wherein said aligning one of the size of the DCI of the first group andthe size of the selected DCI of a second group of DCIs with the othercomprises:

increasing bits in the DCI of the first group, wherein the number of theincreased bits equals to the difference between the size of the DCI ofthe first group and that of the selected DCI of the second group.

(19). The wireless communication method according to (18), wherein saidincreasing bits in the DCI of the first group comprises:

padding bits to the DCI of the first group or increasing CRC (CyclicRedundancy Check) size in the DCI of the first group.

(20). The wireless communication method according to (17), wherein theselected DCI of the second group is a DCI whose size is closest to thesize of the DCI of the first group among DCIs of the second group havingsizes smaller than the size of the DCI of the first group, and

wherein said aligning one of the size of the DCI of the first group andthe size of the selected DCI of a second group of DCIs with the othercomprises:

reducing bits in the DCI of the first group, wherein the number of thereduced bits equals to the difference between the size of the DCI of thefirst group and that of the selected DCI of the second group.

(21). The wireless communication method according to (20), wherein saidreducing bits in the DCI of the first group comprises:

restricting the number of bits in at least one field in the DCI of thefirst group or increasing the granularity of resource allocation in theDCI of the first group.

(22). The wireless communication method according to (17), wherein theselected DCI of the second group is a DCI whose size is closest to thesize of the DCI of the first group among DCIs of the second group havingsizes smaller than the size of the DCI of the first group, and

wherein said aligning one of the size of the DCI of the first group andthe size of the selected DCI of a second group of DCIs with the othercomprises:

adding bits to the selected DCI of the second group, wherein the numberof the added bits equals to the difference between the size of the DCIof the first group and that of the selected DCI of the second group.

(23). The wireless communication method according to (22), wherein saidadding bits to the selected DCI of the second group comprising:

padding bits to the selected DCI of the second group or increasing thenumber of bits in at least one field in the selected DCI. (24). Thewireless communication method according to (17), wherein the first groupof DCIs are DCIs for scheduling sidelink transmission between the userequipment and another user equipment, and the second group of DCIs areDCIs for scheduling transmission between the user equipment and the basestation.

(25). A wireless communication method for a user equipment, comprising:

receiving a first group of DCIs and a second group of DCIs from a basestation; and

detecting blindly the first group of DCIs and the second group of DCIsso as to perform transmission and/or reception based on a rule which isknown by the base station and the user equipment beforehand,

wherein said rule indicates that before being received by the userequipment, the first group of DCIs and the second group of DCIs has beensubject to size alignment comprising: aligning, for each DCI of thefirst group of DCIs, one of the size of the DCI of the first group andthe size of a selected DCI of the second group of DCIs with the otherbased on said rule, if the size of the DCI of the first group isdifferent from the size of each DCI of the second group of DCIs, whereinthe selected DCI of the second group is a DCI whose size is closest tothe size of the DCI of the first group among DCIs of the second grouphaving sizes larger than the size of the DCI of the first group or a DCIwhose size is closest to the size of the DCI of the first group amongDCIs of the second group having sizes smaller than the size of the DCIof the first group.

(26). The wireless communication method according to (25), wherein theselected DCI of the second group is a DCI whose size is closest to thesize of the DCI of the first group among DCIs of the second group havingsizes larger than the size of the DCI of the first group, and

wherein said aligning one of the size of the DCI of the first group andthe size of the selected DCI of a second group of DCIs with the othercomprises:

increasing bits in the DCI of the first group, and the number of theincreased bits equals to the difference between the size of the DCI ofthe first group and that of the selected DCI of the second group.

(27). The wireless communication method according to (26), wherein saidincreasing bits in the DCI of the first group comprises:

padding bits to the DCI of the first group or increasing CRC size in theDCI of the first group.

(28). The wireless communication method according to (25), wherein theselected DCI of the second group is a DCI whose size is closest to thesize of the DCI of the first group among DCIs of the second group havingsizes smaller than the size of the DCI of the first group, and

wherein said aligning one of the size of the DCI of the first group andthe size of the selected DCI of a second group of DCIs with the othercomprises:

reducing bits in the DCI of the first group, and the number of thereduced bits equals to the difference between the size of the DCI of thefirst group and that of the selected DCI of the second group.

(29). The wireless communication method according to (28), wherein saidreducing bits in the DCI of the first group comprises:

restricting the number of bits in at least one field in the DCI of thefirst group or increasing the granularity of resource allocation in theDCI of the first group.

(30). The wireless communication method according to (25), wherein theselected DCI of the second group is a DCI whose size is closest to thesize of the DCI of the first group among DCIs of the second group havingsizes smaller than the size of the DCI of the first group, and

wherein said aligning one of the size of the DCI of the first group andthe size of the selected DCI of a second group of DCIs with the othercomprises:

adding bits to the selected DCI of the second group, wherein the numberof the added bits equals to the difference between the size of the DCIof the first group and that of the selected DCI of the second group.

(31). The wireless communication method according to (30), wherein saidadding bits to the selected DCI of the second group comprising:

padding bits to the selected DCI of the second group or increasing thenumber of bits in at least one field in the selected DCI.

(32). The wireless communication method according to (25), wherein thefirst group of DCIs are DCIs for scheduling sidelink transmissionbetween the user equipment and another user equipment, and the secondgroup of DCIs are DCIs for scheduling transmission between the userequipment and the base station.

The invention claimed is:
 1. A communication apparatus, comprising: areceiver, which, in operation, receives a signal in a search space; andcircuitry, which is coupled to the receiver and which, in operation,detects, in the signal, downlink control information (DCI) in a firstDCI format by using a reference size, the first DCI format being usedfor a sidelink transmission, wherein, the reference size for a firstsearch space is based on a size of a second DCI format being used foranother sidelink transmission, and the reference size for a secondsearch space is based on a size of a third DCI format being used for atransmission between the communication apparatus and a base station. 2.The communication apparatus according to claim 1, wherein one of thefirst DCI format and second DCI format is used for a dynamic schedulingand the other of them is used for a semi-persistent scheduling (SPS). 3.The communication apparatus according to claim 1, wherein the size ofthe second DCI format is a nearest size to a size of the first DCIformat for the first search space, the nearest size being equal to orgreater than the size of the first DCI format.
 4. The communicationapparatus according to claim 1, wherein the size of the third DCI formatis a nearest size to a size of the first DCI format for the secondsearch space, the nearest size being equal to or greater than the sizeof the first DCI format.
 5. The communication apparatus according toclaim 1, wherein zeros of padding bits are added to the first DCI formatuntil a size of the first DCI format with the padding bits equals to thereference size.
 6. A communication method performed by a communicationapparatus, the communication method comprising: receiving a signal in asearch space; and detecting, in the signal, downlink control information(DCI) in a first DCI format by using a reference size, the first DCIformat being used for a sidelink transmission, wherein, the referencesize for a first search space is based on a size of a second DCI formatbeing used for another sidelink transmission, and the reference size fora second search space is based on a size of a third DCI format beingused for a transmission between the communication apparatus and a basestation.
 7. The communication method according to claim 6, wherein oneof the first DCI format and second DCI format is used for a dynamicscheduling and the other of them is used for a semi-persistentscheduling (SPS).
 8. The communication method according to claim 6,wherein the size of the second DCI format is a nearest size to a size ofthe first DCI format for the first search space, the nearest size beingequal to or greater than the size of the first DCI format.
 9. Thecommunication method according to claim 6, wherein the size of the thirdDCI format is a nearest size to a size of the first DCI format for thesecond search space, the nearest size being equal to or greater than thesize of the first DCI format.
 10. The communication method according toclaim 6, wherein zeros of padding bits are added to the first DCI formatuntil a size of the first DCI format with the padding bits equals to thereference size.